Figure 4.

Escape from antibody-mediated neutralization is a key determinant for selection of viral variants after LT. HCVpps were incubated with pretransplant anti-HCV–positive serum or control anti-HCV–negative serum (Ctrl) in serial dilutions for 1 h at 37°C. HCVpp–antibody complexes were then added to Huh7 cells, and infection was analyzed as described in Fig. 3. Calculation of neutralization and determination of background and thresholds for neutralization are described in Materials and methods. End point dilution titers are indicated for each variant. Dashed lines indicate the threshold for a positive neutralization titer corresponding to 1:40. Variants reinfecting the liver graft are depicted in blue, and nonselected variants not detected after transplantation are depicted in white, gray, or black. Means from at least four independent experiments (performed in triplicate) are shown. Statistically significant differences (repeated measures ANOVA) in neutralization between the predominant selected strain and nonselected strains are indicated by asterisks (**, P < 0.001). NI, noninfectious.